<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<script type="text/javascript">
			//
			var str = "today is Monday";
			//
			var reg = /Mon/;
			//
			 var result = str.match(reg);
			 console.log(result);
		</script>
	</body>
</html>
